The present invention is related to a drilling/tapping/unscrewing apparatus in which the drilling, tapping and unscrewing mechanisms are combined into an integral body without switching the power source between forward rotation and forward rotation.
A conventional drilling, tapping or milling apparatus is mounted on a bed. The bit of the apparatus is drivable by a motor to rotate and reciprocally move for drilling or tapping a work piece. Conventionally, the drilling apparatus and tapping apparatus are separately used. In practice, this often leads to inconvenience. In order to solve this problem, an apparatus in which the drilling and tapping mechanisms are combined into an integral body to facilitate operation and save time. For example, Taiwanese Patent Publication No. 193923 discloses a handheld drilling/tapping apparatus having an integral structure. An upper half of the apparatus is a gear case with an opening facing upward. A diaphragm is disposed on one side of the apparatus to define a distributor case. A motor shaft hole, a first transmission shaft hole, a second transmission shaft, a third transmission shaft hole and a through hole are sequentially formed on bottom face of the gear case. A straight barrel is disposed under the transmission shaft holes. A bit barrel is disposed under the through hole. A space in which a motor is disposed is formed under the motor shaft hole. In the above structure, it is necessary to arrange a transmission, an inducing motor and a rotary mechanism between the motor and the transmission shaft for transmitting the power. In addition, it is necessary to arrange a transmission switching unit between the bit and the main body. It is known by those skilled in this field that the cooperation between the transmission and the motor as well as the peripheral mechanisms is complicated. For example, at least a wheel shaft having a shaft hole is disposed on each side of the driven gear of the transmission for cooperating with the tooth structure of rear section of the main shaft. Accordingly, the power can be variably transmitted from the driving gear to the driven gear. Some manufacturers use forward/backward rotatable carbon brush motor or servomotor and speed adjustor to replace the inducing motor and control the transmission. This can somewhat simplify a part of the structure. However, the cost for the motor is very high so that the apparatus is quite expensive. This will affect the competition of the product on the market. In addition, the speed adjustor is very easy to damage.
Therefore, it is necessary to provide a drilling/tapping/unscrewing apparatus in which the drilling, tapping and unscrewing mechanisms are combined into an integral body. The apparatus has simple structure cooperating with a common motor for driving the bit without switching the power source between forward rotation and forward rotation.